Skin Sore Without Rash

Anthropology: Our inert genetic

Many human gene variants are much older than assumed

From: Scientific American, March 2011

penetrate more deeply into the secrets of our genetic research genetic material, the more will find more surprises them. In the March issue of "Scientific American" of American human geneticist Jonathan K. Pritchard tells of the University of Chicago on the origin of the genetic diversity of today's humans. Like a number of colleagues Pritchard looks for traces of the distribution history of Homo sapiens in the genome. Mutations, for example, gene variants that may bear this out.

Experts previously suspected, many clear genetic differences between some groups of people were present in the evolutionary scale occurred only recently, before more than a few thousand years - because that is adjustment to new environments would represent conquered. But this is not the case. The meticulous thinning of many Genomes revealed very few examples of the genes - and in particular the gene pool of populations - lately so clearly changed. Among the few blatant cases, any adjustment in blood Tibetans who makes life easier in 4000 meters height. It emphasizes the connection, like the adaptation to digest milk in adulthood in different populations of animal breeders. Most

but appearances are deceiving. For example, a mutation was important for lighter skin in Europe is not only, as people moved further and further north, there to absorb vitamin D formation still had enough UV radiation. Rather, this genetic variant was already somewhere in the south just off the Urwurzel of Europeans, and soon after leaving Africa, and shortly after the East Asians were later split off.

appear at all, most of today's genetic adaptations yet to come from times that date back at least several tens of thousand years. Pritchard describes in non-Africans, three general patterns in the genome - or ramifications of lines of development - that reflect the spread of Homo sapiens rather well. A lot changed after leaving Africa at least 60,000 years ago - this heritage to this day impressed by much. In addition, features a common origin of Europeans and West Asians from clear. The third pattern marks the East Asian, Australian and American indigenous peoples.

But as explained by today's diversity? Pritchard and his colleagues suspect that evolution plays in adjustment processes, each with a large number of genes, more precisely, that usually involve hundreds or even thousands of genes at a feature. The contribution of each gene can then be negligible. Already, scientists have identified 50 genetic factors for body size, and they expect a lot more.